It is known to employ apparatus which utilizes a capillary tube of predetermined length mounted on a holder for collecting a predetermined accurately measured volume of fluid sample, for example plasma, serum or blood for subsequent testing as shown in U.S. Pat. No. 3,045,494. It is also known to employ capillary tubes for measuring capillary quantities of blood, for example up to 100 or more microliters. However, assemblies do not provide means for filling the tube and for flushing it into a diluent to remove all of the sample from the tube without losing any portion thereof -- see for example U.S. Pat. No. 3,475,127.
It is important to obtain quantities of samples for blood testing which require volumes of more than 30, 40 or 50 microliters. However, when using capillary tubes of volumes greater than 50 microliters the tube becomes overly long, is fragile and readily breaks when handled. Samples for 100 microliters are generally obtained in microliter syringes which accurately measure the required volume. However, no means is provided for flushing the sample from the syringe so that all of the sample is discharged into a desired volume of diluent.